This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The mechanical properties of spider silk are very sensitive to changes in spinning conditions and environmental parameters such as relative humidity of the air and temperature. The goal of this study is to further the understanding of the microscopic basis of the exceptional mechanical properties of spider silk and how changes of these macroscopic properties induced by e.g. water absorption and temperature can be understood as a result of microscopic structural rearrangements. For this project, we propose to characterize the spider silk of Nephila clavipes (the golden orb weaver) and Argiope aurantia obtained from (a) naturally spun orb webs, (b) forced silking and (c) abseiling, using Wide Angle and Small Angle X-ray Scattering (WAXS and SAXS) methods. Because some material and mechanical properties of spider silk have been shown to be evolutionarily correlated, this work will provide novel and useful addition to the literature and reveal performance implications for this exceptional biomaterial.